This invention relates to adsorbent regeneration and halocarbon recovery from carbonaceous adsorbents as assisted by hydrocarbon gases. More particularly, this invention relates to a process of regenerating carbonaceous adsorbents bearing trace amounts of halocarbon compounds by purging the adsorbents with hydrocarbon gases such as propane, butane and pentane and the possible recovery of the halocarbon from this hydrocarbon stream.
Carbonaceous adsorbents are used routinely for the adsorption of halocarbons from gaseous and aqueous streams as used in air and water purification processes. After use, these adsorbents are either disposed of or, if economically feasible, are regenerated.
Conventional regeneration processes include thermal processes and solvent extraction processes. During a thermal regeneration process the adsorbent is heated at temperatures up to 450.degree. C. with an inert gas such as nitrogen or air allowing the halocarbons to become physically desorbed from the carbonaceous adsorbent.
During a solvent extraction process, the adsorbent is flushed with a liquid solvent, essentially dissolving the adsorbed halocarbon; the halocarbon can then be recovered from the solvent.
The above conventional processes have many drawbacks. For example, the thermal regeneration process has high energy requirements and is, therefore, expensive. Moreover, many adsorbed halocarbons are thermally labile and frequently decompose at high temperatures, thereby eliminating any potential for subsequent recovery and re-use of the halocarbons.
The solvent extraction process has many steps. After the adsorbent is flushed with a liquid solvent, the halocarbons must be removed from the solvent. This recovery is frequently difficult. In addition, the spent solvent must be disposed of or further treated. As a result, adsorbent regeneration by the solvent extraction process has many steps, which require equipment, manual labor and is, therefore, costly. Moreover, because the regeneration of certain carbonaceous adsorbents has proven cumbersome and expensive, frequently the spent adsorbent has been simply discarded. Accordingly, it would be advantageous to provide an adsorbent regeneration process which eliminates the need for high temperatures or spent solvent disposal and which is, at the same time, economically competitive to the simple disposal of carbonaceous adsorbents.
It is therefore a primary object of this invention to provide a new, cost effective process for regeneration of carbonaceous adsorbents. Another object of this invention is to recover the previously adsorbed halocarbons for subsequent reuse.